Monitoring of vital signs is essential for patients in intensive care units, for patients suffering from chronic illnesses, and in post-operation situations. For this purpose, sensors are commonly attached to a patient's body that are usually connected to a bedside monitor which shows the state of the received vital parameters. Nowadays, the sensors and the monitor are connected by wires. This reduces the patient's mobility and makes the work of nursing staff more difficult, for example, because all the wired connections between the sensors and the monitor must be set up.
In order to increase the patient's mobility, to make the work of nursing staff easier and to get a flexible sensor system in aspects as quantity of sensors, diversity of applications, etc., the concept of body sensor networks (BSN) has been developed. In body sensor networks, the communication between the sensors attached to a patient or between a sensor and the monitor is based on wireless communication links. In order to ensure interoperability on the one hand in between the sensors and on the other hand between the sensors and the monitor, an open standard is typically used as communication protocol. Open standards that are for example employed are: the IEEE 802.15.1 standard which is also known as Bluetooth, the WiFi standard (IEEE 802.11), and the Zigbee standard (IEEE 802.15.4).
As the applications that the sensors of a body sensor network will carry out are critical, the communication between the monitor and the sensors must be reliable at least in a short range around the patient in order to ensure correct monitoring. Other wireless networks or other devices employing a wireless communication technology might however generate interfering radio signals that might disturb the communication between the sensors of the body sensor network or between a sensor and the bedside monitor of the body sensor network. A body sensor network might for example employ the Zigbee standard for communication. The frequency band employed by the Zigbee standard lies within the ISM radio band around 2.4 GHz. A device, e.g. a laptop, in close vicinity to the body sensor network might for example employ the Bluetooth standard. The device therefore generates radio signals that interfere with the radio signals in accordance with the Zigbee standard and might cause a malfunction of the communication in the body sensor network.
Another interfering technology might be due to a microwave oven which emits radio waves with frequencies in the ISM band.
As the applications that the sensors carry out are critical, the communication between the monitor and the sensors must be reliable at least in the short range around the patient to ensure a correct monitoring. As a consequence, interfering technologies should be detected by the body sensor network or, more precisely, by one or more of the sensors or by the monitor of the body sensor network in order to ensure a proper operation of the network. The term interfering technology is within this document used in order to refer to a source which generates radio signals that might interfere with the radio signals used for wireless communication in between a wireless body sensor network and that might therefore disturb the communication in the wireless body sensor network.
The document US 2006/0089103 A1 discloses a radio frequency source detector which is built with the purpose of detecting and analysing RF (radio frequency) signals in order to determine the source of interference. The source detector is useful for installing and troubleshooting a wireless local area network (WLAN) or similar communication devices. The detector includes a receiver to receive RF signals from unknown RF sources, a processor for determining the level and characteristics of the RF signals and for determining the identities of unknown RF sources, and a display on which the processor displays the identities of the RF sources.
It is an object of the invention to provide an improved device for detecting interfering sources of radio signals and to identify the underlying technology. It is a further object of the invention to provide an improved method of detecting interfering sources of radio signals and identifying the underlying technology.